The University of Pennsylvania Health System (UPHS) provides care to over 2,500 HIV-infected individuals at the Hospital of the University of Pennsylvania, Presbyterian Medical Center, the Philadelphia Veterans Administration Medical Center, Pennsylvania Hospital, and Children's Hospital of Philadelphia. The Clinical Core of the Penn Center for AIDS Research will maintain and expand a longitudinal database that currently includes demographic, behavioral, and clinical information on over 1,600 HIV-infected men, women, adolescents, and children receiving care in the UPHS. The Clinical Core Database can be used to identify potential subjects for study or, when linked with three other campus databases with in-depth clinical information, can be used as a tool for independent clinical investigation. We will expand this Database to include information on 3,000 HIV-infected individuals. In addition, the Clinical Core has created a Specimen Repository, linked to the Database, which contains several thousand banked plasma, serum, and peripheral blood mononuclear cells (PBMCs) collected semiannually. We will continue to collect serum and plasma samples at regular intervals in the future. Fresh PBMCs will be collected by investigator request, and a PBMC sample from each participant will be obtained for preparation of DNA suitable for host genetic analyses. These resources will be used to promote interdisciplinary and translational research on the Penn campus. The Database will be expanded to include new data elements in three areas, metabolic complications of antiretroviral therapy, hepatitis co-infection, and adherence and at-risk behaviors in order to support on-going and planned research of young and new HIV investigators. The Clinical Core will coordinate the collection of a wider range of patient material, including cells collected by apheresis, genital secretions, and adipose tissue. Penn and regional investigators with interests in HIV pathogenesis, antiretroviral therapy and its complications, opportunistic infections, neurological and psychiatric complications, adherence, HIV risk behaviors and transmission, and quality of life will be brought together to expand the focus of current research and establish collaborations across fields of interest.